The invention relates to the use of combinations of the known medicinal agents prazosin, 2-[4-(2-furoyl)piperazin-1-yl]-4-amino-6,7-dimethoxyquinazoline, and pirbuterol, 2-hydroxymethyl-3-hydroxy-6-(1-hydroxy-2-t-butylaminoethyl)pyridine, for improved bronchodilation in mammals, including humans.
Prazosin and its pharmaceutically acceptable salts were disclosed as antihypertensive agents in U.S. Pat. No. 3,511,836 and U.S. Pat. No. 4,092,315. Pharmacological studies on prazosin hydrochloride were reported by Scriabine et al., Experientia, 24, 1150 (1968); by Cohen, J. Clin. Pharmacol. J. New Drugs, 10, 408 (1970); Cavero et al. Life Sci., 27, 1525-1540 (1980); and in "Prazosin: Pharmacology, Hypertension and Congestive Heart Failure," Rawlins, Ed., Grune and Stratton, New York, 1981.
The bronchodilator, pirbuterol, was disclosed in U.S. Pat. No. 3,700,681, U.S. Pat. No. 3,786,160. Its use for treatment of congestive heart failure was disclosed in U.S. Pat. No. 4,175,128. Pharmacological studies on pirbuterol were reported by Constantine et al., J. Pharmacol. Exp. Ther., 208, 371 (1979). A comparative study in treating respiratory disease was reported by Dyson and Mackay, Brit. J. Dis. Chest, 74, 70 (1980) and its use in treatment of cardiac failure by Colucci et al., N. Engl. J. Med., 305, 185 (1981); Nelson et al. Eur. Heart J., 3, 238 (1982) and Weber et al., Circulation, 66, 1262 (1982).